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Chapter 7. The Annotations Alternative

So far, we’ve been working with the XML
mapping document as the starting point for our examples. In cases
where you’re starting with just a concept and can leave the details of
creating data tables and data objects to Hibernate, that remains a great
option. The advent of Java 5’s flexible Annotation support opened up a very
interesting alternate approach, however, especially for the common case
where you’ve already got some objects written by the time that you’re
thinking about how to save them to a database.

Hibernate Annotations

If you haven’t started using annotations yet, the code examples in
this chapter will look a little strange, so it’s worth spending a minute
or two to discuss the history and purpose of Java annotations. Basically,
an annotation is a way to add information about a piece of code (in the
Java world, typically a class, field, or method) to help tools understand
how the code is being used, or to enable automation that saves you work.
Rather than having a separate file, like a persistence mapping, to
maintain in parallel with your source code, you would put that information
right in the source code it affected. This way you are in no danger of a
file separate from your source code becoming out of synch. Before Java 5
included robust support for this style of coding, people found a “back
door” way of achieving it, by leveraging the extensible nature of
the JavaDoc tools.

JavaDoc was a form of annotation that existed in Java ...

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